Habitat Suitability Criteria for Native Fishes in Intermediate-Sized Arizona Rivers
Endemic fishes of the arid southwestern United States have rapidly declined due to anthropogenic stressors. Identifying the habitat conditions needed by these species is critical for their successful management. Habitat suitability criteria are commonly used to conserve species of interest. Therefore, developing habitat suitability criteria for native fish species across multiple rivers permits better understanding of how different environments are occupied under various circumstances. Over 1,200 sites were sampled using pre-positioned electrofishing devices during the 2017 summer low-flow period to identify relationships among fish presence and habitat variables (depth, velocity, and substrate class). We developed stream-specific and generalized criteria for Longfin Dace Agosia chrysogaster, Speckled Dace Rhinichthys osculus, and Desert Sucker Pantosteus clarki, in central Arizona streams (Eagle Creek, Blue River, Tonto Creek). Because of low number of sites containing native fishes, stream specific criteria could not be developed for the Verde River for all species, Eagle Creek for Sonora Sucker; and Tonto Creek for Speckled Dace. Furthermore, there were not enough sites occupied by Roundtail Chub Gila Robusta, Loach Minnow Rhinichthys cobitis, or Spikedace Meda fulgida, in any of the study streams to develop stream-specific or generalized HSC. Optimal (central 50% of range used) and suitable (central 95% of range used) ranges within each habitat variable were calculated for each stream, based on the occurrence of each species. In general, Longfin Dace occupied depths of 9.00 – 54.75 cm (14.25 – 27.25 cm) velocities of 0.00 – 0.63 m/sec (0.11 – 0.31 m/sec), and substrate (modified Wentworth scale) of 0.5 – 4.3 (2.1 – 3.3). Speckled Dace occupied depths of 8.25 – 74.00 cm (17.00 – 34.25 cm) velocities of 0.00 – 0.74 m/sec (0.16 – 0.43 m/sec), and substrate of 0.0 – 4.5 (2.2 – 3.6). Desert Sucker occupied depths of 9.00 – 45.00 cm (15.25 – 25.00 cm) velocities of 0.09 – 0.72 m/sec (0.21 – 0.44 m/sec), and substrate of 1.0 – 4.6 (2.5 – 3.7). Only 13-53% of generalized habitat suitability criteria transferred to the various streams. Therefore, criteria are most accurate when developed for the stream of interest. Field work and data analysis for this project was completed fall 2018, a thesis was completed January 2019 and the work was published. These data are now being examined to help develop HSC for native species in the Verde River.